Behaviour of Nanostructure Polyoxometalates Containing Co, Ni, and Cu as aPowerful and Stable Catalysts for Hydrogen Evolution Reaction in Acidic andAlkaline Solutions

A new form of [PW11MO39]5‒@Ru-reduced graphene oxide (rGO) (M: Co, Ni, and Cu) wasprepared by deposition of [PW11MO39]5‒ on the surface of Ru-rGO. The different behaviours ofthe polyoxometalates (POM) in acidic and alkaline media were studied for hydrogen evolutionreaction (HER). Transmission electron microscopy, scanning electron microscopy, energydispersive X-ray spectroscopy, X-ray diffraction pattern and infrared spectroscopy were used forcharacterization of the nanocomposites. The electrocatalytic properties of the nanocompositestoward HER were studied by voltammetry and electrochemical impedance spectroscopy. Thekinetic parameters were computed from the Tafel plots, and the possible mechanisms of the HERwere considered. The results showed that the HER on [PW11MO39]5‒@Ru-rGO electrodes obeyedVolmer-Heyrovsky mechanism. It was taken that the enhancements in the rate of the HER on themodified electrodes may be associated with the presence of the nanoparticles of POM on theelectrode surface and enhancement of the surface area. These results demonstrated that thenanocomposites could be effective HER catalysts in acidic and alkaline media with consideringgreen chemistry. These have good catalytic capacities, durability, favorable kinetics, and lowprice.

Keywords:

Polyoxometalates , Ru-reduced graphene oxide nanocomposites , reduced grapheneoxide , Electrocatalyst , Hydrogen evolution reaction